Many electronic devices use a number of separate integrated circuit (IC) chips. Typically, each IC chip is mounted individually in a separate package that is connected to a printed circuit board which provides power and signal interconnections to the IC chips. However, when a device requires a large number of IC chips, individually packaging and mounting each chip greatly increases the area on the printed circuit board required to interconnect all the chips. Additionally, as device speeds increase, it is more important to minimize the path lengths between IC chips themselves, as well as between the IC chips and other electronic components connected to them.
To decrease printed circuit board space, distance between IC chips and complexity of interconnections, many devices now use multichip modules (MCMs) that incorporate a number of IC chips into one package. Integrating a number of IC chips into one package reduces the distance between IC chips, thus permitting greater device speeds. The MCMs usually provide power and signal interconnections to the individual IC chips from an underlying ceramic substrate.
MCMs may be two-dimensional, that is all the IC chips of a package are mounted on a planar substrate, or three-dimensional, where IC chips are mounted above or below a ceramic substrate, another IC chip, or an interposer. An interposer is a structure on which various electronic components and interconnections are formed and is usually located between an IC chip and a ceramic substrate, another interposer, or a printed circuit board.
As the switching speed of devices increases, it is important to provide a decoupling capacitor in close proximity to the IC chips of the multichip module. Decoupling capacitors serve as charge reservoirs to support instantaneous current surges that invariably accompany simultaneous circuit switching. Conventionally, decoupling capacitors have been incorporated into the ceramic substrate which increases the complexity of the ceramic substrate, thus decreasing production yields, as well as uses up space on the ceramic substrate, which is at a premium.
Further, during device production, it is inevitable that one or more components of the device produced will be defective, which may increase as components decrease in size. Devices containing a defective component then have to be discarded, or at the very least, the part(s) of the device containing the defective component has to be discarded. For example, if a ceramic substrate has one or more defective decoupling capacitors, it has to be discarded. As such, production yields will similarly be decreased.
Therefore, techniques for producing electronic devices that maximize available space while maintaining proper path lengths between components and minimize the effects of defective components would be desirable.